The present invention relates to a soft magnetic bulky alloy for use as a core of a magnetic head or a magnetic core of a pulse motor, and a method of manufacturing such a soft magnetic bulky alloy.
Generally, the characteristics required for the soft magnetic alloy for use as a core of a magnetic head, a magnetic core of a pulse motor, a transformer or a choke coil are high saturation magnetization, high magnetic permeability, low coercive force, and malleability for shaping into a thin form. In view of the above, various alloys have been studied in the course of developing such alloys.
Conventional materials for use in the above applications are crystalline alloys, such as Sendust, Permalloy or silicon steel. In recent years, Fe or Co based amorphous alloys have also been used.
Regarding magnetic heads, there has been a demand for magnetic materials for higher performance magnetic heads which can cope with magnetic recording media having a high coercive force resulting from an increase in the recording density.
For pulse motors, transformers or choke coils, there has been a demand for materials exhibiting excellent magnetic characteristics which can cope with a reduction in the size and an increase in the frequency.
However, Sendust suffers from a disadvantage in that the saturation magnetization thereof is as low as about 11 kG, although it exhibits excellent soft magnetic characteristics. Permalloy, which has an alloy composition exhibiting excellent soft magnetic characteristics, also has a saturation magnetization as low as about 8 kG. Fe-Si alloys have inferior soft magnetic characteristics, although they have a high saturation magnetization.
Co-based amorphous alloys have an insufficient saturation magnetization, which is about 10 kG, although they exhibit excellent soft magnetic characteristics. Fe-based amorphous alloys tend to exhibit insufficient soft magnetic characteristics, although they have a high saturation magnetization, which is 15 kG or above. Further, amorphous alloys are insufficient in terms of the heat stability and this deficiency must be overcome. Thus, conventionally it is difficult to provide a material exhibiting both high saturation magnetization and excellent soft magnetic characteristics.
In view of the above, the present inventors have noted the soft magnetic alloy described in Material Transactions, JIM Vol. 32 No. 1, January 1991. This alloy has an Fe-M-B based fine grain phase containing Fe, B and M where M is at least one element selected from a group consisting of Ti, Zr, Hf, V, Nb, Ta, Mo and W. This type of alloy exhibits excellent soft magnetic characteristics and a high saturation magnetization. However, since the alloy is generally manufactured in the form of a ribbon, it is difficult to apply to the core of the magnetic head, to the magnetic core of a pulse motor or to the core of a transformer due to the difficulty in machining of the ribbon.